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Re-read the whole request in direct IO mode when IO uring returns partial result (#6853)

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Summary:
If both direct IO and IO uring are enabled, when IO uring returns partial result, we'll try to read the remaining part of the request, but the starting address/offset of the remaining part might not be aligned to the block size, in direct IO mode, the unaligned offset causes bug.
Pull Request resolved: https://github.com/facebook/rocksdb/pull/6853

Test Plan: run make check with both direct IO and IO uring enabled, this is covered by one of the continuous tests.

Reviewed By: anand1976

Differential Revision: D21603023

Pulled By: cheng-chang

fbshipit-source-id: 942f6a11ff21e1892af6c4464e02bab4c707787c
This commit is contained in:
Cheng Chang 2020-05-18 17:23:22 -07:00 committed by Facebook GitHub Bot
parent b9d65f5aa6
commit ada700b906
1 changed files with 21 additions and 12 deletions
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33
env/io_posix.cc vendored
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@ -189,19 +189,19 @@ bool IsSyncFileRangeSupported(int fd) {
/*
* DirectIOHelper
*/
#ifndef NDEBUG
namespace {
bool IsSectorAligned(const size_t off, size_t sector_size) {
return off % sector_size == 0;
assert((sector_size & (sector_size - 1)) == 0);
return (off & (sector_size - 1)) == 0;
}
#ifndef NDEBUG
bool IsSectorAligned(const void* ptr, size_t sector_size) {
return uintptr_t(ptr) % sector_size == 0;
}
} // namespace
#endif
} // namespace
/*
* PosixSequentialFile
@ -276,7 +276,7 @@ IOStatus PosixSequentialFile::PositionedRead(uint64_t offset, size_t n,
ptr += r;
offset += r;
left -= r;
if (r % static_cast<ssize_t>(GetRequiredBufferAlignment()) != 0) {
if (!IsSectorAligned(r, GetRequiredBufferAlignment())) {
// Bytes reads don't fill sectors. Should only happen at the end
// of the file.
break;
@ -711,13 +711,22 @@ IOStatus PosixRandomAccessFile::MultiRead(FSReadRequest* reqs,
// comment
// https://github.com/facebook/rocksdb/pull/6441#issuecomment-589843435
// Fall back to pread in this case.
Slice tmp_slice;
req->status =
Read(req->offset + req_wrap->finished_len,
req->len - req_wrap->finished_len, options, &tmp_slice,
req->scratch + req_wrap->finished_len, dbg);
req->result =
Slice(req->scratch, req_wrap->finished_len + tmp_slice.size());
if (use_direct_io() &&
!IsSectorAligned(req_wrap->finished_len,
GetRequiredBufferAlignment())) {
// Bytes reads don't fill sectors. Should only happen at the end
// of the file.
req->result = Slice(req->scratch, req_wrap->finished_len);
req->status = IOStatus::OK();
} else {
Slice tmp_slice;
req->status =
Read(req->offset + req_wrap->finished_len,
req->len - req_wrap->finished_len, options, &tmp_slice,
req->scratch + req_wrap->finished_len, dbg);
req->result =
Slice(req->scratch, req_wrap->finished_len + tmp_slice.size());
}
} else if (bytes_read < req_wrap->iov.iov_len) {
assert(bytes_read > 0);
assert(bytes_read + req_wrap->finished_len < req->len);